The new Crossrail trains are live today. They're just running on the Liverpool Street to Shenfield part of the route at the moment, until the tunnels under London launch in December next year.

So what makes these new trains so special? They're seven carriages long, but will be nine carriages long when Crossrail fully launches. They have have air-conditioning, CCTV, Wifi and 4G, dedicated spaces for wheelchair users and they're fully interconnected, walk-through carriages.

The class 345 trains were supposed to launch last month but were delayed to allow for further testing. Many saw the tantalising new machines passing through local stations, some (train experts) even mistook them for being in service.

However, don't expect every TfL Rail journey to be on a nice and comfy class 345 from now on. As with the S Stock on the tube's Metropolitan, District, Hammersmith & City and Circle lines, there's a transition period where both the old and new trains run.

Here's what the Mayor of London Sadiq Khan had to say on the launch. "I'm delighted that our first state-of-the-art Elizabeth line train has entered service on the TfL Rail service. It gives Londoners a first look at a new service that will transform travel across London and the south east when the line opens. The Crossrail programme remains on time and on budget, and the huge success of this project shows how vital it is for the whole of the country that we also push ahead with Crossrail 2."